JPS6168398A - Growing method of cubic type boron nitride crystal - Google Patents

Abstract

PURPOSE:To obtain crystals having small distribution width of grain sizes and excellent mechanical characteristics at high productivity by despising cubic boron nitride particles in a specific form and growing the same until the crystal particles having the specific grain size are obtd. CONSTITUTION:Many recesses 2 for contg. the cubic boron nitride seeds are perforated to a flux material plate. The recesses 2 are regularly perforated at equal intervals in such a manner that the spaces l between the adjacent recesses are 20-200mu as the spaces between the adjacent crystal particles after the crystal growth. The flux material plate embedded with the seeds 3 in the recesses 2 is superposed on a low pressure phase (hexagonal) boron nitride plate 4 in such a manner that the surface disposed with the cubic boron nitride seeds is positioned on the boundary (opposite) side. Such superposed plates or the laminated plates laminated with the plural superposed plates are subjected to the pressure and temp. conditions in the stable region of the cubic boron nitride crystal, by which the cubic boron nitride crystals are grown.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the production of cubic boron nitride (hereinafter referred to as [
This invention relates to a method of growing crystals using cubic boron nitride particles as seeds when synthesizing CBNJ.

Conventional technology When synthesizing CBN 'i using the hydrostatic method, it is possible to control the number of generated nuclei and grow them at a temperature and pressure very close to the phase equilibrium line, which results in a well-shaped structure with few inclusions. This is important in obtaining good crystals in good yield. Crystal growth using seeds is an effective means of controlling the number of nuclei.

CBH crystal growth methods using the hydrostatic pressure method include a temperature difference growth method and a thin film growth method. The former is a method in which seeds and raw material sources are exposed to a solvent substance with a temperature gradient, and the seeds on the lower temperature side are fully grown. Low-pressure phase (hexagonal) boron nitride (hereinafter referred to as "HBN") is dissolved to form 1(B
This is a method of growing CBN crystals based on the solubility difference between N and CBN. In the latter case, the crystal size basically depends on the time required for synthesis, the amount of cubic nuclei generated, and the raw material H supplied.
Depends on the amount of BN. It is possible to control the number of nuclei by using seeds for nuclear generation, but the particle size may be reduced due to factors such as uneven distribution of nuclei, time lag in the growth of nuclei at their positions within the sample, and interference between nuclei or growing particles. It is difficult to obtain uniform cubic boron nitride crystals in good yield.

Further, even if the number of nuclei can be completely controlled by using seeds, good crystals cannot be obtained if crystal growth is performed in a region with a high degree of supersaturation of boron nitride concentration.

The shape of the crystal becomes worse, and more impurities such as solvent substances, raw material substances, and air bubbles are included. In order to reduce the degree of supersaturation, it is necessary to maintain temperature and pressure conditions very close to the phase equilibrium line. However, in industrial ultra-high pressure synthesis equipment, it is extremely difficult to constantly measure the temperature and pressure in the reaction zone and control them to desired values.

Also, by mixing the solvent substance, the raw material HhN, and the CBN seeds,
A known method is to mold a mixture into a cylinder, load it into a high-pressure device, and grow crystals therein. This method is
It is difficult to disperse the seeds uniformly in the mixture, which tends to cause variations in crystal growth.

Problems to be Solved by the Invention The purpose of the present invention is to solve the problems of the conventional technology as described above, and to develop CBN crystals with a small particle size distribution width and excellent crushing strength and other mechanical properties. The purpose of the present invention is to provide a method that enables molding with high productivity.

The method for growing CBN crystals according to the present invention involves arranging a large number of CBN seeds on at least one surface of a solvent material plate and a T (BN plate) such that the CBN seed arrangement surface is located on the interface side. A polymeric board in which a solvent material board and an HBN board are stacked together, or a laminate in which a plurality of such polymeric boards are laminated, or a board in which a large number of CBN seeds are arranged on the surface of a board made of a mixture of a solvent material and HBN, or CBN is produced by laminating a plurality of such plates under pressure and temperature conditions in the CBN stability region.
A method for growing crystals, in which CBN particles with a particle size of 150 μm or less are grown as CBN seeds at substantially equal intervals, and the distance between adjacent crystal grains after crystal growth is 20 to 200 μm.
1.5 of the seed particle size.
It is characterized in that it is grown until CBN crystal particles having a diameter twice or more are obtained.

CBN seeds are placed on the surface of at least one of the solvent material plate and the HBN plate or on the surface of the plate of a mixture of such solvent material and HBN at substantially equal intervals and between adjacent crystal grains after crystal growth. are arranged regularly so that the intervals between them fall within a predetermined range.

Various methods can be used to regularly arrange the CBN particles that serve as seeds. The most preferred method is to drill a large number of holes on the surface of the plate and place one CBN particle in each hole. A mechanical method using a micro-diameter drill etc. can be used to make holes in a solvent material plate, an HBN plate, or a plate of a mixture of solvent material and 1BN. In addition to mechanical methods, etching methods including photo-etching, electrical discharge machining methods, radar machining methods, etc. can be applied.

In addition, when using nitride or boron nitride as the solvent substance, it is difficult to drill holes directly into the solvent substance, so prepare a separate auxiliary plate, drill holes in it, and insert the seeds.
Use this in conjunction with a solvent material plate, or
All you have to do is drill holes in the BN board. As an auxiliary plate, Cu, Co
, Ni, Ta, W, etc. can be used.

CBN seeds can be placed in each well by scattering them on a perforated plate and applying appropriate motion. In this case, the CBN seeds are preferably coated with an electrically conductive material, in particular plated with metal. Plating with metal gives the seeds a rounded shape and provides antistatic properties, making them easier to insert into the holes. When a metal is used as a solvent substance, it is desirable that the metal to be plated is the same metal.

Furthermore, coating the CBN seeds with metal or the like has the advantage of cutting off direct contact between the CBN seeds and the raw material HBN under high-pressure crystal growth conditions. The metal in this case does not have to be the same as the solvent metal. The coating material is generally an alkali metal, an alkaline earth metal, or an element from group I or group II of the periodic table. It's 2 degrees Celsius when it closes. 5.

Although a through hole may be provided in place of the recessed hole, it is more advantageous to handle the seeds if the hole is not a through hole.

Instead of drilling the holes as described above, it is also possible to press the seeds directly into the board. It is also possible to apply a small amount of an adhesive substance to the surface in the form of a whole spot, and to adhere the bare or metal-coated seeds to the spot. Further, regular placement can be performed using a mesh having appropriate openings or using an automatic electronic component placement device.

FIG. 1 shows a state in which a number of holes 2 into which CBN seeds are to be placed are bored in a solvent plate. In FIG. 2, a large number of concave holes 2 are arranged at substantially equal intervals, and the distance t between adjacent concave holes is 20 to 200 μm as the distance between adjacent crystal grains after crystal growth.
The figure shows a state in which the holes are drilled regularly so that m is formed. The arrangement pattern of the concave holes may be as shown in FIG. You can take a turn.

1 solvent material plate for embedding CBN seeds 3 in concave holes 2, CB
Place the superimposed polymers as they are, or as shown in Fig. The pressure in the CBN crystal stability region as a multi-layered laminate
CBN crystals are grown under temperature conditions.

The CBN seeds can be placed on the surface of the HBN plate or on both the solvent material plate and the HBN plate rather than the solvent material plate. Alternatively, it can be placed on the surface of a plate made by compression molding a mixture of solvent substance powder and HBN powder using a hot press or the like.

In the present invention, firstly, the CBN seeds are arranged at substantially equal intervals and the distance between adjacent crystal grains after crystal growth is 20 to 2.
It is important to arrange them regularly so that the distance is 00 μm. If the spacing between crystal grains is less than 20 μm, interference between seeds during the crystal growth process may cause the grains to stick together and inhibit growth, making it difficult to obtain high-quality grown crystals with a small particle size distribution. If the spacing exceeds 200 μm, local unbalance in supersaturation occurs, which tends to cause variations in crystal growth. Therefore, the particle size distribution tends to become large. Moreover, productivity decreases.

The second main feature of the present invention is that CBN seeds with a particle size of 150
The goal is to grow at least 1.5 times (in terms of particle size) using particles smaller than μm. By performing such crystal growth, it is possible to obtain crystalline gold of high quality, particularly superior crushing strength and other mechanical strength. Seed particle size is 150μ
When it is larger than m, it becomes difficult to cover the catalyst film uniformly. Preferably, those having a particle size of 10 to 50 μm are used. Further, the growth rate is not particularly limited, but in terms of particle size, it is generally 1.5 to 10 times, particularly preferably about 3 to 5 times.

Solvent substances include lithium and other alkali metals, calcium,! Alkaline earth metals such as gnesium, and their nitrides (L 13N I Ca 5 N 2
etc.), composite nitrides (LiCaBN2, Li3BN2, etc.) can be used.

In addition, in order to suppress the excessive growth rate of crystals and obtain well-shaped crystals, 31. Mo, Zr, 'ri.

At, Sn, PL, Pb, B+C, and their silicides, borides, and nitrides can be added in small amounts.

CBN crystals are grown under pressure and temperature conditions in the CBN stable region. Generally, temperatures in the range of 1250 to 1850°C and pressures in the range of 45 to 70 kb are employed.

In the above system, CB that can be expected in the reaction system
If the number of dianthus is determined so that the line growth 11 of N matches the product of the number of seeds and the average desired growth amount per seed, then
It is possible to obtain CBN with a targeted particle size in the distribution. Total growth (expected value)? To know it systematically, you can synthesize it by changing the final load.

In order to obtain a large amount, within the range allowed by the synthesis equipment,
It is necessary to increase the final load. Therefore, if the seed density is too high, the grown grains will interfere with each other. In addition, as another method for narrowing the particle size distribution, it is effective to take into account the temperature distribution and pressure distribution of the reaction part, and change the spacing between the seed arrays in the radial direction and the vertical direction, and the size of the seeds as appropriate.

Effects of the invention By regularly arranging the CBN particles that serve as seeds so as to satisfy the above requirements, variations in crystal growth conditions that occur for each seed are reduced, and micro variations in temperature and pressure within the reaction space are also reduced. However, there is no interference between the seeds caused by the growth of seeds that are too close to each other, and it is possible to obtain ncBN crystal particles having a very uniform particle size distribution. Moreover, by performing such crystal growth, a high quality CBN crystal with excellent mechanical strength can be obtained.

Example Next, the present invention will be explained with reference to Examples.

Example 1 A reactant was placed in a graphite cylinder with an outer diameter of 2866 mm, an inner diameter of 26 m, and a length of 38 mm, and a diameter of 26 mm and a thickness of 1.4 mm.
++m HBN molded disk, diameter 26mm, thickness 1.5
Lithium Calcium Pyronite 2ide (LiCa)
BN2) A large number of molded body disks were alternately stacked and arranged.

In this reaction system, the HBN molded disk was preliminarily filled with 0.0 mm at the intersection of the base grains so that the center spacing was 0.4 m.
, in a concave hole of 15wφX 0.25 rras d,
One CBN particle serving as a seed with a particle size of 90 to 110 μm was placed in each container. Both ends were kept warm with waxstone plates, and an iron lid was placed on the tube, which was then attached to a belt-type ultra-high pressure synthesis device and pressurized, while electricity was applied to the graphite cylinder to raise the temperature by indirect heating.

The reaction conditions in this case are a pressure of 57 kb and a temperature of about 1
The temperature was 450°C.

The reaction time was 15 minutes.

As a result, approximately 69 CBNs were obtained, but approximately 40 staff members were
It was concentrated in the range of 50 to 300 μm. The yield of brown, transparent, blocky, high-quality crystals was approximately 404 in the conventional method using a molded body obtained from a mixture of BN powder and the above-mentioned L I Ca BN 2 powder (with the same amount of seeds). In the above-mentioned example of the present invention, the improvement was 804, which was twice as high.

Example 2 In the same graphite cylinder as that used in Example 1, a BN molded disk with a diameter of 26 mφ and a thickness of 1.5 MR (a BN molded disk and a cylinder with a diameter of 26 mφ and a thickness of 1.5 MR) were placed as reactants. Ca5B door.

A large number of molded body disks were alternately stacked and arranged. During stacking, a copper plate with a diameter of 26 mφ and a thickness of 0.3 m was interposed between the BN disk and the Ca, 82N4 disk.

In this copper (catalyst) plate, holes of 0 and 1 diameter were drilled in advance at the intersections of the base grains so that the center spacing was 0.4 wm (the tips of the holes were drilled partially through them). CB that becomes a seed in
N particles (particle size: 60 to 80 μm) were placed in an amount of t-1 each. Both ends are insulated with wax stone plates, then covered with an iron lid, attached to a belt-type ultra-high pressure synthesis device, and pressurized.
Electricity was applied to the graphite cylinder and the temperature was raised by indirect heating. The reaction conditions were set as follows. That is, the pressure was set to e50 kb, the temperature was set to 1500°C, and then the pressure was gradually increased to 57 kb over 20 minutes. The results were similar to those in Example 1. Example 3 CBN crystals were grown by the same method as in Example 2. However, instead of the copper plate, 26 gates in diameter φ and 0.3I in thickness
Using II11 magnesium (catalyst) plate, on this plate,
0.2 at the intersection of the base grains so that the center distance is 0.5 m.
A hole of wsφ was drilled. Particle size as seeds: 30-40μm
CBN particles coated with Cu to obtain a particle size of 100-120μ
m was used. The reaction conditions were set as follows. That is, the pressure 'fr: 50 kb and the temperature 1
500°C, then gradually increase the pressure to 500°C over 40 minutes.
It increased to 7kb. The results were similar to those in Example 1.

Comparative Example 1 A CBN crystal was grown in the same manner as in Example 2. However, CBN with a particle size of 300 to 350 μm as seeds
Using particles, holes of 0.5 wφ were bored in the copper plate at the intersections of the base grains so that the center spacing was 0.9 mm. The reaction conditions were set in the same manner as in Example 2.

The yield is 6 gr, and most of the grown crystals have a grain size of 700-8.
It was 00 μm. Crystal growth was non-uniform and blocky crystals were hardly obtained.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a solvent material plate in which holes are drilled for placing cubic boron nitride (CBN) seeds, and Figure 2 is a plan view of the solvent material plate shown in Figure 1. Fig. 3 shows the solvent material plate shown in Fig. 1 and Fig.
) is a sectional view showing a state in which a large number of plates are alternately stacked. 1: Solvent material plate, 2: Hole, 3: CBN seed, 4: H
BN board.

Claims (1)

[Claims] 1. A large number of cubic boron nitride seeds are arranged on the surface of at least one of the solvent material plate and the low-pressure phase boron nitride plate, and the surface on which the cubic boron nitride seeds are arranged is an interface. A polymer plate consisting of a solvent material plate and a low-pressure phase boron nitride plate stacked side by side, or a laminate of a plurality of such polymer plates, or a plate of a mixture of a solvent substance and a low-pressure phase boron nitride plate. A plate with a large number of cubic boron nitride seeds arranged on its surface, or a laminate of multiple such plates, is used to grow cubic boron nitride crystals under pressure and temperature conditions in the cubic boron nitride stable region. A method comprising cubic boron nitride particles having a grain size of 150 μm or less as cubic boron nitride seeds at substantially equal intervals, and an interval between adjacent crystal grains after crystal growth of 20 μm.
Cubic boron nitride crystals are grown until cubic boron nitride crystal particles are regularly arranged so as to have a diameter of ~200 μm and have a diameter of 1.5 times or more the seed grain size. How to grow. 2. A large number of concave holes are formed on at least one surface of the solvent material plate and the low pressure phase boron nitride plate at substantially equal intervals, and the distance between the peripheries of adjacent concave holes is equal to the distance between adjacent crystal grains after crystal growth. The holes are regularly drilled at intervals of 20 to 200 μm,
The method for growing cubic boron nitride crystals according to claim 1, wherein one cubic boron nitride seed is placed in each recessed hole. 3. A method for growing a cubic boron nitride crystal according to claim 2, wherein a large number of concave holes are formed on the surface of the solvent material plate. 4. A method for growing cubic boron nitride crystals according to claim 2 or 3, in which cubic boron nitride seeds are plated with metal and placed in each of the recesses.